llvm/tools/llvm-xray/xray-graph.h

//===-- xray-graph.h - XRay Function Call Graph Renderer --------*- C++ -*-===//
//
//                     The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
// Generate a DOT file to represent the function call graph encountered in
// the trace.
//
//===----------------------------------------------------------------------===//

#ifndef XRAY_GRAPH_H
#define XRAY_GRAPH_H

#include <vector>

#include "func-id-helper.h"
#include "llvm/ADT/DenseMap.h"
#include "llvm/ADT/SmallVector.h"
#include "llvm/Support/raw_ostream.h"
#include "llvm/Support/Program.h"
#include "llvm/XRay/Trace.h"
#include "llvm/XRay/XRayRecord.h"

namespace llvm {
namespace xray {

/// A class encapsulating the logic related to analyzing XRay traces, producting
/// Graphs from them and then exporting those graphs for review.
class GraphRenderer {
public:
  /// An inner struct for common timing statistics information
  struct TimeStat {
    uint64_t Count;
    double Min;
    double Median;
    double Pct90;
    double Pct99;
    double Max;
    double Sum;
  };

  /// An inner struct for storing edge attributes for our graph. Here the
  /// attributes are mainly function call statistics.
  ///
  /// FIXME: expand to contain more information eg call latencies.
  struct EdgeAttribute {
    TimeStat S;
    std::vector<uint64_t> Timings;
  };

  /// An Inner Struct for storing vertex attributes, at the moment just
  /// SymbolNames, however in future we could store bulk function statistics.
  ///
  /// FIXME: Store more attributes based on instrumentation map.
  struct VertexAttribute {
    std::string SymbolName;
    TimeStat S;
  };

private:
  /// The Graph stored in an edge-list like format, with the edges also having
  /// An attached set of attributes.
  DenseMap<int32_t, DenseMap<int32_t, EdgeAttribute>> Graph;

  /// Graph Vertex Attributes. These are presently stored seperate from the
  /// main graph.
  DenseMap<int32_t, VertexAttribute> VertexAttrs;

  struct FunctionAttr {
    int32_t FuncId;
    uint64_t TSC;
  };

  /// Use a Map to store the Function stack for each thread whilst building the
  /// graph.
  ///
  /// FIXME: Perhaps we can Build this into LatencyAccountant? or vise versa?
  DenseMap<llvm::sys::ProcessInfo::ProcessId, SmallVector<FunctionAttr, 4>>
      PerThreadFunctionStack;

  /// Usefull object for getting human readable Symbol Names.
  FuncIdConversionHelper &FuncIdHelper;
  bool DeduceSiblingCalls = false;
  uint64_t CurrentMaxTSC = 0;

  /// A private function to help implement the statistic generation functions;
  template <typename U>
  void getStats(U begin, U end, GraphRenderer::TimeStat &S);

  /// Calculates latency statistics for each edge and stores the data in the
  /// Graph
  void calculateEdgeStatistics();

  /// Calculates latency statistics for each vertex and stores the data in the
  /// Graph
  void calculateVertexStatistics();

  /// Normalises latency statistics for each edge and vertex by CycleFrequency;
  void normaliseStatistics(double CycleFrequency);

public:
  /// Takes in a reference to a FuncIdHelper in order to have ready access to
  /// Symbol names.
  explicit GraphRenderer(FuncIdConversionHelper &FuncIdHelper, bool DSC)
      : FuncIdHelper(FuncIdHelper), DeduceSiblingCalls(DSC) {}

  /// Process an Xray record and expand the graph.
  ///
  /// This Function will return true on success, or false if records are not
  /// presented in per-thread call-tree DFS order. (That is for each thread the
  /// Records should be in order runtime on an ideal system.)
  ///
  /// FIXME: Make this more robust against small irregularities.
  bool accountRecord(const XRayRecord &Record);

  /// An enum for enumerating the various statistics gathered on latencies
  enum class StatType { COUNT, MIN, MED, PCT90, PCT99, MAX, SUM };

  /// Output the Embedded graph in DOT format on \p OS, labeling the edges by
  /// \p T
  void exportGraphAsDOT(raw_ostream &OS, const XRayFileHeader &H,
                        StatType T = StatType::COUNT);
};
}
}

#endif // XRAY_GRAPH_H